1. Field of the Invention
The present invention relates to an image recording apparatus and, more specifically, to an image recording apparatus capable of exposing the surface of a photosensitive recording medium to reflected light from a document to record the information of the document on the surface of the photosensitive recording medium.
2. Description of Related Art
Methods of recording the image information of a document on the surface of a photosensitive recording medium by exposing the surface of the photosensitive recording medium to reflected light from the illuminated document have been disclosed in, for example, U.S. Pat. Nos. 4,399,209 and 4,440,846.
The photosensitive characteristic of such a photosensitive recording medium, in general, has a nonsensitive region in which the exposure density is not increased when the exposure is below a predetermined level, a sensitive region where the exposure density is proportional to the amount of exposure and a saturation region in which the exposure density is saturated on a fixed level when the exposure is above a predetermined level as shown in FIG. 1. When the exposure is in the nonsensitive region, the gradation of an image formed on the surface of the photosensitive recording medium is unsatisfactory. A method of improving the gradation by additional exposure, i.e., auxiliary exposure, is disclosed in U.S. patent application Ser. No. 20956 (Filing date: Mar. 2, 1987) now abandoned in favor of U.S. patent application Ser. No. 4,935,749. This method and system of auxiliary exposure, however, requires an additional auxiliary exposure device. Japanese Patent Laid-open No. 63-291048 discloses a method employing a dot screen to improve gradation. However, an image formed of dots is unsatisfactory in definition.
On the other hand, it is generally known that reflected light reflected from a document by specular reflection (glare) does not carry any image information. In particular, when the original has, for example, a glossy finish, light supplied by the light source does not enter the material which contains the image but is instead reflected by the glossy finish. This specular reflection, or glare, does not contain any image information. Accordingly, the luminous intensity of the light source must be increased, which requires a high-tension power source and increases power consumption.
Furthermore, the aforesaid photosensitive characteristic of the photosensitive recording medium forms unavoidable pseudocontours on the boundaries between the nonsensitive region and the sensitive region and between the sensitive region and the saturation region. These pseudocontours appear to be, for example, the end or boundary of an object in the image, but in reality are merely boundaries between portions of the recording medium which have been exposed to adequate and either too little or too much light.